This is one of my favourite folksongs! I used to sing all of the verses to myself when I was a child.

A couple of quick explanations:
As with all the Norwegian folksongs there are several versions around, all with a varying number of verses. This one has more than 30 verses (it is not actually that many when you consider that each verse only consists of two lines; the rest is a repeated refrain.)

The asterikses in the translation are explained beneath.

A quick summery of the story:
little Kjersti is the (very!) young daughter of a rich farmer (in some versions she is so small that she even has trouble turning the heavy keys in the keyholes). One day the mountain king comes to the farm. The farmer greats him and offers him ale and vine but the mountain king declines this and says that he is more interested in Little Kjersti. The farmer tries to protest but the mountain king threatens to set his farm on fire and in the end little Kjersti is sent along with the mountain king. When they arrive in the mountain Kjersti is offered a drink poured into a rich red and gold cup (in older days fine cups were made out of horns with metal- or gold fittings, hence the word "horn") into which the mountain king´s people have placed three wild grains (villar can mean wild but could also indicate that they carry the ability to confuse). By drinking this Kjersti forgets who she is and where she comes from and when they ask her she states that she was raised in the mountain, is betrothed to the mountain king and wishes to live and die there.

The last line of the refrain:..der leikar det. This is a very tricky term to translate. To “leike” means to play, both games and also sometimes instruments, but it can also denote music or sounds used by the creatures of the underworld to lure humans. The creatures of the Norwegian underworld (Huldra, Nøkken, Fossekallen and the Mountain King) were all known to use music to lure humans down to their world, and certain places in nature it was believed that you could sometimes hear or sense their activity. So the lines literally means “deep beneath the rocks it leiker”.